From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A40A0C433E1 for ; Mon, 18 May 2020 11:31:12 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 79565207E8 for ; Mon, 18 May 2020 11:31:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="iC+a+Ash"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="XF7NkBh2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 79565207E8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=0TiqsQaca9sHJfvqE3KUXNXIOfodwvQMOJaKy0cBZEc=; b=iC+a+AshunlebO 3rz8d8/Y6sBwoTMJQybf6wiO152rwK+p8H6EIqHUxBF7bs5wfaODNfm/vWObRL6xVkfo082mhYvV5 VB71b4n/1z7kut7zByYP/wuhXbsnN28mPMucqXk1MuYSgCIbtnGD4Gm6h/3521jaLx2FCzmmi3QhC 1m3zB2GA5NU+YwevRFq+L8fxDcqps4voMif2Mqhb9+ZVfnPxaOd+JHtdRvT/h4SvsRiuIpmUOiEPx ChhGMCFtTTZryQoMRAFxQrRQukXvP22DHZ+lCNcrIR93aTprKTOM+Keq5xlh7Hsv6DWxWWqG9IdI3 66729vVRFfExH3s9Z5UQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jadzE-0000qJ-4P; Mon, 18 May 2020 11:31:12 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jadzB-0000pt-B7 for linux-arm-kernel@lists.infradead.org; Mon, 18 May 2020 11:31:10 +0000 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D8B0920756; Mon, 18 May 2020 11:31:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589801468; bh=mA5LuL+NZ4U22EpIeu1yY/QuHzmG+4ZlK35nDxAZ3lY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XF7NkBh2RpP7Djhlw6gtpIkyVTqRimk+VriVrbaCTcWm/aslkIwjKrKCrs5T2jQ4v B9xYMQiqzJR3hkd0a/BLad5a4SW3AkDSXqzrObZQ4NfAO9jrtvsYsOiJ/lEIeuhY3z c01YbNXnW0VfZBr3F1izfcNFuOr49q89HEZl1o5I= Date: Mon, 18 May 2020 12:31:03 +0100 From: Will Deacon To: Vladimir Murzin Subject: Re: [PATCH v4 24/26] arm64: mte: Introduce early param to disable MTE support Message-ID: <20200518113103.GA32394@willie-the-truck> References: <20200515171612.1020-1-catalin.marinas@arm.com> <20200515171612.1020-25-catalin.marinas@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200518_043109_407280_63228DDB X-CRM114-Status: GOOD ( 17.88 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Szabolcs Nagy , Catalin Marinas , Kevin Brodsky , linux-mm@kvack.org, Andrey Konovalov , Vincenzo Frascino , Peter Collingbourne , Dave P Martin , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, May 18, 2020 at 12:26:30PM +0100, Vladimir Murzin wrote: > On 5/15/20 6:16 PM, Catalin Marinas wrote: > > For performance analysis it may be desirable to disable MTE altogether > > via an early param. Introduce arm64.mte_disable and, if true, filter out > > the sanitised ID_AA64PFR1_EL1.MTE field to avoid exposing the HWCAP to > > user. > > > > Signed-off-by: Catalin Marinas > > Cc: Will Deacon > > --- > > > > Notes: > > New in v4. > > > > Documentation/admin-guide/kernel-parameters.txt | 4 ++++ > > arch/arm64/kernel/cpufeature.c | 11 +++++++++++ > > 2 files changed, 15 insertions(+) > > > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > > index f2a93c8679e8..7436e7462b85 100644 > > --- a/Documentation/admin-guide/kernel-parameters.txt > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > @@ -373,6 +373,10 @@ > > arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards > > Format: ,, > > > > + arm64.mte_disable= > > + [ARM64] Disable Linux support for the Memory > > + Tagging Extension (both user and in-kernel). > > + > > Should it really to take parameter (on/off/true/false)? It may lead to expectation > that arm64.mte_disable=false should enable MT and, yes, double negatives make it > look ugly, so if we do need parameter, can it be arm64.mte=on/off/true/false? I don't think "performance analysis" is a good justification for this parameter tbh. We don't tend to add these options for other architectural features, and I don't see why MTE is any different in this regard. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel